/Engine/Source/Runtime/Engine/Classes/Engine/World.h
Called whenever a world is registered to an audio device. UWorlds are not guaranteed to be registered to the same audio device throughout their lifecycle, and there is no guarantee on the lifespan of both theUWorldand the Audio Device registered in this callback.
typedef TMulticastDelegate_TwoParams< void, const [UWorld](API\Runtime\Engine\Engine\UWorld) *, [Audio::FDeviceId](API\Runtime\Engine\FDeviceId) > FOnWorldRegisteredToAudioDevice